A plurality of rotary union structures exist for supplying a heat exchange fluid, such as oil, to a rotating body or load. In the past, one type of self-supported rotating union includes a pair of carbon graphite bearing structures which support and retain the alignment of the rotary union housing with respect to the rotating a rotor or shaft and wherein the rotor or shaft member encircles a siphon pipe through which the hot oil is removed from the interior of a rotating body or load. Such rotating unions may include a pair of carbon graphite bushing bearings and a seal assembly which also acts as a thrust bearing assembly to absorb the thrust forces generated by fluid pressure within the union. The rotary housing is mounted and aligned with respect to the rotating rotor or shaft by the pair of carbon graphite bushing bearings to maintain the housing and the rotor in alignment during operation. However, the front graphite bushing bearings are not in contact with the pumped fluid and, accordingly, such rotary unions have a limited operational temperature of a maximum of about 450° F. and approximately 200 RPMs.
Another attempt to provide a self-supported rotary union for communicating a heat exchange fluid to a rotating drum is a rotary union that includes anti-friction rotating bearings located within bearing housings which provide support for the rotary union's housing with respect to the rotating load. When such roller bearing structures are utilized to support and align the rotary housing in a union supplying hot oil to a load, it has been found that the roller bearing structures are generally operable to a maximum operating temperature of 300° F. Thus, such roller bearing structures require auxiliary lubricating and cooling systems to supply a lubricating oil or a high temperature lubricating grease to the bearing assembly. Accordingly, such complicated rotary unions require expensive high temperature lubricating greases and also result in a change in physical property and performance according to the temperature of the union. Therefore, such union structures are expensive to manufacture and possess a shortened service life.